Wet weather in Spa has put pay to a lot of the running the teams were hoping to do in order to evaluate new parts.

Mercedes bought a surprise package to Spa in the form of a drag reduction device much like the lauded Lotus device.

Due to the weather conditions getting shots of the WO3 in action were slim but as we can see from the images below the device mimics the effect Lotus are trying to achieve.

Just like Lotus an adaption to the engine cover has been placed around the airbox in order to recapture air along with any being spilt off throttle (This occurs when the opening can no longer receive anymore air and so the airflow tumbles back out and over the sides of the airbox)
Airbox Spillage being captured by these ducts also helps tidy up the airflow that may become turbulant and affect the Rear Wings effectiveness.

The air that passes through these ducts is then sent down the engine cover before being diverted up the Periscope to the Rear Wing. Unlike the Lotus version Mercedes periscope stops short of the underside of the Rear Wing. (It's unclear at present if this is part of the design process or a different Rear Wing will be used in conjunction with the device)

As the periscope was taped up (Due to weather) it's unclear how big or the orientation of the blow holes but what is clear is, if the periscope does indeed drop short of the Rear Wing the blowing effect may cover an increased area than the Lotus variant.

In short if I'm right by being able to blow the rear wing via these pylon holes it allows for the Rear Wing to run at a steeper angle of attack (AoA) this is because the holes decrease the boundary layer build up and so increase downforce. As speed exponentionally increases the holes get to a point whereby they can't provide enough airflow for the wings AoA and so the wing stalls (Critical Angle / CL Max) Downforce is reduced and so is the drag. This allows for the car to ultimately attain a higher speed (I'd predict 5-10KMH)

Mercedes will continue to use DDRS in tandem with this device thus aiding with further drag reduction whilst DRS is unavailable.

The mainstream media still seem intent on calling these devices DDRS (Double DRS) or Super DRS as I first coined it. For me that is a name that should only be used for the original Mercedes system as it requires the use of DRS for it's secondary usage to come into play.

The Lotus team simply call theirs the 'Device' so perhaps we should by using the acronym DRD? Drag Reduction Device?

As much of the traffic to my site atthe moment centres around the Lotus DDRS/Passive F Duct system Ithought for my pre Spa Musings I'd talk a little about thepast iterations of such a system.

We can go as far back as 2008/09 to seethe first signs of these devices emerging with both McLaren and Toyota fielding passive ducting on their cars for more co-efficient designs.

The designs of all the systems have always centred around the premise of the central 15cm of the wing being free to allow holes. The Toyota and McLaren designs of 08/09 featured such holes in the15cm region which would increase downforce in the central portion of the wing by injecting airflow below the normal wing gaps.

As we can see from the pictures below of the McLaren from behind at Monaco in 09 the slot gap projects the same width on the rear as it does at the frontal collection area. McLaren angled the wing fences on the wing in order to augment the airflow across the wing. The slot gap delays the onset of boundary layer separation caused by the wing being run at additional angle of attack, resulting in a downforce gain with the slot acting as a third slot gap separating the wing plane. The rear wing planes angle of attack and the size of the hole in the wing are crucial at higher speed. As the speed increases the air provided by the hole gets to a point where a blockage occurs, (ie no more air can be vented) this causes the boundary layer to separate and thus the wing stalls.

In aerospace the term 'stall' is used in a different context to the way the F1 fraternity use it. In terms of an F1 wing a stall occurs when the angle of attack is too large (same as aerospace) whereas when an airplane wing stalls, lift is lost due to the critical AoA being exceeded and the flow separates creating drag. This is where the major confusion occurs as principally when an F1 wing stalls just like an airplane it creates drag but essentially there is a resultant loss of downforce. The loss of downforce makes the wing less efficient and so cancels out the drag further giving a top speed advantage of between 5-10km/h dependent on the system.

Above: Toyota TF108 - Monaco 2008 you can see the central duct in the 15cm free zone

Above: McLaren MP4-24 - Monaco 2009 Shows the passive duct used by McLaren which was the genesis for the 2010 driver controlled F Duct

It is widely accepted that drag reduction is the desired effect of both passive and F ducts but it is entirely plausible downforce is also gained as a result of careful management of the rear wings angle of attack (AoA).

The F Duct systems of 2010 (Once again with McLaren at the fore, using their 2009 experience) were a development of this principle. Adding the driver as the controlling influence allowed the team to make the slots on the rear of the wing larger meaning they could gain more downforce from an aggressive wing AoA whilst blowing the wing. When the driver covered the hole in the cockpit the airflow to the rear wing would cease and drag would be reduced.

Above: McLaren MP4-25 - 2010 Slot gaps extend across the top plane of the rear wing

The FIA changed the rules in 2011 to stop the F Duct systems by placing a minimum radius of 100mm on the wing planes, this stops the teams from adding the slots that ran almost the length of the wing planes but the 15cm central zone still remains open to interpretation. Obviously with the allowance of DRS the FIA assumed that teams would no longer pursue this method of downforce enhancement / drag reduction. However the system that Lotus have been testing since Hockenheim uses these exact principles.

Lotus Passive Pylon Duct

With the 100mm Radius rule stopping the placement of elongated blow holes on the rear of the planes it would appear that only the original straight through style duct would be viable in order to create the F Duct effect (Like the Toyota and McLaren versions shown above). However smartly the Lotus system takes cues from the original F Duct concepts but rather than using holes/slots in the wing planes these are placed in the pylon that connects the engine cover to the Rear Wing. The holes blow tangentially from the pylon across the wing span.

Blowing the air across the wing plane reduces the boundary layer which in combination with the steep angle of attack of the wing creates more downforce. At a certain threshold the blowholes reach a point where they can't produce enough air to stop the wing from stalling and so drag is reduced. Careful management of the wing AoA and the size of the pylon blow holes will decide the speed threshold at which the wing loses downforce and drag.

Above: Lotus E20 - Hockenheim Showing the rear wing painted with Flo-Viz, due to the Flo-Viz you can see in the central section the airflow separating

Above: Lotus E20 Airbox 'Ears'

As I have talked about previously the 'Ears' are used as a way of recovering airflow when off throttle. The main airbox entry blocks when off throttle and the air that usually tumbles over the side and disturbs the airflow heading towards the rear wing now enters the ear ducts. This obviously helps by keeping the system in loop during the Braking and Turning phases generating more downforce.

Lotus placed their exhausts in a more aerodynamically neutral position than say McLaren this season and as such have a more consistent aerodynamic platform. Realising that without EBD the downforce level is inconsistent the team have decided to achieve downforce in a more consistent way via the Rear Wing (Including the Beam Wing) and airflow en mass over the Diffuser.
The addition of the pylon for the passive F Duct required the team to have the engine cover finish further back toward the wing and so a funnel now presents itself at the Monkey Seat / Beam Wing. This Funnel and Monkey Seat act together acting as a mini diffuser atop of the beam wing creating more downforce.

In order to see how Lotus (nee Renault) came up with their current system lets quickly look back at their 2010 efforts. The team actually used two variants of the rear wing drag reduction system back in 2010, they ran the passive style system that McLaren used in 09 and then a full blown F Duct system. Their full blown system used similar Airbox ears we now see on the LotusE20. The pylon being used as a means of carrying the air to the under side of the Rear Wing also featured in the original 2010 designs but this was structural in the 2010 versions. This however must have given the team a head start in CFD and Wind Tunnel in terms of modeling the structures involved.

Above: Renault R30 - 2010 (Hungary) Passive System

Above: Renault R30 - 2010 Showing the similar Airbox 'Ears' being used currently on the Lotus E20

Above: Renault R30 - 2010 F-Duct System

Something to think about?....

Before the FIA increased deflection tests and then latterly mandated the size of the slot gap teams intentionally designed the top flap to flex under load closing the gap between it and the main plane. This had the desired effect of stalling the wing and reducing downforce/drag as the AoA of both wings combined became too large.
As a parting thought on this subject I propose the use of a trailing edge Gurneythat although dimensionally would be within the regulations (The Latter part of article 3.10.1: Once this section is defined, ‘gurney’ type trim tabs may be fitted to the trailing edge. When measured in any longitudinal cross section no dimension of any such trim tab may exceed 20mm.)would be different to the perceived Rear Wing 'Gurney'

Above: McLaren introduced a Red Bull style Diffuser gurney in Hungary in order to aid the generation of downforce

If we take the current design of the Red Bull, Ferrari & McLaren diffuser gurneys as inspiration these Gurneys act as a method of increasing downforce through airflow injection. Using a similar design approach at the trailing edge of the rear wing flap could produce more downforce . Similarly it could be used in conjunction with the flap to stall the main plane by the use of flex. The Gurney doesn't have the same deflection tests as the flap and main plane and so could be designed so that the gap is open to generate downforce and closes at higher speeds. The 'Gurney' has no real restrictions placed on it's design and so could have a small or large chord as long as it doesn't extend beyond the 20mm mandated.The height of the gurney and the slot gap left between it and the flap could be adjusted in order to suit the characteristics of the downforce/drag reduction required.
As usual these are my thoughts and should be taken with a pinch of salt as I haven't got access to CFD etc in order to access the general principles and most importantly the effects of DRS when the top flap is open may make the idea mute. In my eyes the Gurney could offer a source of both additional downforce and drag reduction by lending principles from former designs. Images Copyright: Sutton Images

Mercedes are a company that have
invested hugely in F1 over the last few years in response to buying
the Championship winning Brawn GP. In terms of Mercedes interest in
F1 they had for a long time aligned their selves with the McLaren
team, having some of their SLR road range carrying the McLaren logo.
Mercedes also owned a 40% stake in the McLaren outfit with McLaren
effectively acting as their works team. Ron Dennis having moved
across from the F1 team at the end of 2008 to focus on a road car
project meant that the two had a conflict of interest. McLaren and
Mercedes amicably agreed that McLaren would purchase back around 30%
of the shares and so Mercedes found their way into owning the
majority of the Brawn GP team (with only the directors of Brawn GP owning small
percentage shares in the Mercedes GP team)

Brawn GP was the legacy of a hugely
expensive project formerly owned by Honda who had also elected to buy
the team from the well established BAR who in 1999 had bought the
team from Ken Tyrell. This year (2012) is the third iteration under
the Mercedes marque which as a project was supposed to bear fruit as
a manufacturer in its own right rather than just be an engine
manufacturer. (Just as its previous owners Honda were looking to do)
The trouble is always one of transition, time and of course money.
Lets look a further back down the line to see how Mercedes current
struggles can also be attributed to the past and where they are going to go from here.

2009

2009 was a difficult time for the
Brackley based team, on one hand they were winning races and taking
the plaudits for building a fantastic car but on the other hand they
were restructuring and losing staff to fall in line with the loss of
Hondas money and support.

In 2008 Honda had realized their car was a
dog and switched their focus early to the RA109/BGP001 knowing a new
set of regulations gave them a blank canvas on which to base their
design. They also accrued some of the team that had been working
within the Super Aguri team that had folded in 2008. This was
believed to be pivotal in Honda's design approach for the 09 car with
the Super Aguri crew rumoured to have bought the DDD concept to Ross
Brawns attention (whilst others who left Super Aguri made their way
to Toyota and Williams). Honda threw resources and money at the 09
contender although the Japansese marque will never be remembered for
the success as Ross Brawn the man who lead the buyout had his name
above the door. In fairness to Honda they didn't simply withdraw from
the sport but looked for another source to continue their work and
keep their employees in a Job. Several avenues were approached but
eventually it was to be Ross himself who would take the the team on.

Honda continued to financially support
the team well into the season with around 100 million still filtering
to the team into 09. The team were unable to align themselves with a
title sponsor in such a short time frame meant they attained sponsors
on a race by race basis. This may not seem the most business savvy
approach but can be a lucrative one if deals can done for each race.
Richard Branson's Virgin brand was the one to be most associated with
the team during the 09 season but again this was a case of
sponsorship on a race by race basis although Branson would have had
you believed otherwise (shrewd marketing on his behalf)

With the 09 season being the first in a
new rule set Honda had obviously ploughed large resources into making
the 09 car successful. The largest problem Brawn faced when trying to
get the car to the Melbourne grid was the engine supply as Honda had
no allegiances beyond their own works team they no longer had to
supply anyone in F1. Ross initially went to his previous employers
Ferrari but swiftly realized that integrating that engine into the
car would be a monumental task. The next port of call was Mercedes at
which point from the specifications it became clear fitting the
Mercedes FO108W would be much easier and so began a partnership with
Mercedes that would later see them become the works team. It's widely
reported that although fitment of the Mercedes engine was easier than
the Ferrari counterpart it still had compromises notably the CoG was
raised and crank centre position was far from ideal. The team were
desperate to utilize the gearbox designed in house as it's design was
both light and centered around the utilisation of the DDD concept.
Both Jenson and Rubens were vocal in their admiration for the
Mercedes engine which was reportedly much more linear in it's power
delivery giving much better driveability. The Honda engine was always
well known for having a very peaky top end performance and this
obviously showed when the team transitioned to the Mercedes
powerplant. It remains unclear whether Honda intended to use KERS but
the designs shown of the RA109 place the energy storage (batteries)
lined up in series in the bottom of the nosecone. A novel solution
considering the weight and cooling complications this may have had.
http://www.greencarcongress.com/2010/11/hondas-f1-kers-motor-60-kw-21000-rpm-7-kg.html

The KERS technology was not passed onto
the Brawn outfit and/or would have been difficult to implement with
the Mercedes engine due to the crank position, cost and purely
timing, KERS wasn't possible for the team to introduce in 09. As
other teams struggled to utilize their own KERS systems Brawn were
able to move ballast around their car but mainly loaded their bib/tea
tray area with ballast echoing the weight distribution ethos that the
RA109 equipped with KERS may have had. KERS packages in 09 weighed
around 30KG's which is a substantial amount of weight when you
consider being able to put this wherever you like in the car. The
likes of McLaren & Ferrari had to place their heavy systems in
certain places to utilize cooling and weight distribution.

It turned out that Red Bull would be
Brawn GP's closest rival during 2009 with Brawn leading the charge
from Australia and the DDD being the coup of the season finding a
loophole in the regulations relating to diffuser overall height and
using a section above the starter hole to create an additional deck
in order to create more diffuser volume. This was much to the
frustration of all but Williams and Toyota who too had similar
designs and interpreted the rules in much the same way. Ross Brawn as
part of the Technical Working Group (TWG) had throughout the draft
stage of the technical regulations for 09 pointed out that the area
should be looked at due to the potential it possessed to create
downforce. He later argued when the teams tried to retrospectively
ban Double Deck Diffusers 'I told you so'. The ruling by the FIA to
allow DDD's was a huge frustration to a lot of the teams as they knew
the lengths that would need to be taken to integrate it into their
own cars. The development and implementation of DDD's would take
several races and lead to a total shift in the development path most
teams would need to take for the season. However it was clear that
the BGP001's diffuser was the silver bullet and needed for the
fastest package. Red Bull were seemingly the most frustrated having
designed what was essentially the quickest non DDD car. Adrian
Newey's bug bear was not that he hadn't come up with DDD it was that
he could neither get it banned or quickly adapt his RB5 to have it,
due to them adopting pull rod rear suspension. Whilst the Red Bull
team poured resources into integrating DDD the Brawn team just tried
to stay consistent as they couldn't afford the massive cost of a
development race and perhaps capitalized on the change from
Bridgestones grooved tyres to a more traditional slick tyre whereas
others struggled.

It turned out that the early advantage that Brawn
got in 09 was enough to take both Drivers and Constructors titles
making only minor changes to the BGP001 throughout the season. The
BGP001 considering it's late change to Mercedes power remained very
reliable with the team only having 2 retirements all season only 1 of
which was a mechanical failure (Rubens Barrichello at Turkey with a
rear suspension failure)

Throughout 09 Brawn had realized that
the high chassis / nose / suspension of the RB5 was worth pursuing
for 2010. They ran a sight bar / nose ridges to test during Free
Practice sessions in 09 in order to assess whether this was the right
design process to follow. It's difficult to know from the outside how
much effort Brawn had to sacrifice on their 2010 car in order to win
the 09 championships.

Mercedes decided to purchase Brawn GP
but the announcement wasn't made until after the 2009 season had
concluded. 2009 had been a hard fought battle with Red Bull and
although the team took the title, it had come at the expense of
balancing the development of the 09 car further into the season than
perhaps was really wanted.

2010

The WO1, Mercedes first car in F1 since
the 50's was flawed for many reasons although the Brawn GP team had
been world champions in 09 they neither had the resources or money to
contest the battle for 09 and produce another championship winning
car for 2010. When design focus was needed to be placed on the 2010
car during the 09 season both Jenson Button and Rubens Barrichello
were at the helm of the BGP001 neither of which drove in Mercedes
first season compromising the W01 with traits that perhaps their new
driver line up of Michael Schumacher and Nico Rosberg wouldn't like.
Michael returned to the sport in 2010 after a 3 year absence in which
time he spent the first year as an advisor to Ferrari and continued
his motorsport journey on two wheels until at which point he had an
accident and injured his shoulder. It was afterall this injury that
had stopped his return for Ferrari in 09 for the injured Massa at
Ferrari and reignited Michaels passion to be in F1.

The DDD diffusers that were the
catalyst for Brawn GP's success in 09 were already now fully
integrated into the lead teams packages, aided by Exhaust blown
diffusers some of the teams now had a huge chunk more rear downforce
than the W01.

Several rules were bought in, in order
to make adjustments from the rules first laid down in 09:

The front tyres were reduced in width
from 270mm to 245mm in order to remove some mechanical grip from the
front of the cars.

A new points system and qualifying
process was bought in to both balance the larger field and add
further entertainment for the fans.

Refuelling would also be excluded. This
would see teams carrying around 160-180 Litres of fuel from the start
of the race rather than the 70-90 Litres they carried in 09. This in
itself required a major rethink in order to balance the requirements
of qualifying and the race and selecting wheelbase/weight
distribution correctly would give one team more of an advantage than
it's competitors.

The 2010 season saw all the teams agree
on an exclusion of KERS due to the heavy costs involved for the 3 new
teams entering the sport.

The largest changes from the BGP001 to
the WO1 came in the form of the higher ridged nose/bulkhead as I
alluded to earlier that the team had taken a cue from Red Bull and in
a latter upgrade a blade style roll over hoop with twin airbox
entries either side.

It was McLaren who stole the limelight
in regard to innovation for 2010 with their F Duct system which
reduced drag when the driver placed his knee/hand over a cockpit
aperture moving airflow normally designated for the engine cover exit
and instead blowing the rear side of the rear wing plane via the
shark fin style engine cover which was attached to the rear wing
plane. All teams realised that the device was a very clever
interpretation of the rules and set about designing their own
variant. This turned out to be a protracted battle as McLaren's tub
was designed with this in mind whereas the other teams were not.
Mercedes decided that they couldn't effectively develop a close loop
(driver operated) F Duct system into their package without further
compromising their current aero (due to the low slung blade roll
hoop) and so set about adding an open loop (passive) rear wing drag
reduction duct.

They teased everyone at first with a loop that went
from the main plane to top plane but it would appear no other ducting
lead from other areas of the cars to this section. The design they
eventually used was remarkably similar to a design that McLaren ran
in Monaco 2009 who cited this to be their original inspiration behind
the current F Duct. Ducts like these are activated by air speed and
so when the car reaches a certain velocity the air moving through the
duct to the slots on the rear wing plane reduce drag. If indeed this
arrangement was passive then I see no reason that Mercedes having
experience with the device couldn't fit it or a similar system to the W03 to reduce drag
on straights that DRS is unavailable just as Lotus are looking to do
with their DDRS system. The slot and ridges are formed in the central
15cm free zone that allows for the DRS pylons etc and so should still
be legal under the 2012 regulations.

2011

This year was the first year proper for
Mercedes as a team and with a car designed with Nico and Michael in
mind. Gone was the controversial blade style roll hoop/airbox in
favour of a more conventional one. Even though both Force India and
Team Lotus had taken cues from the W01 with their 2011 challengers and ran with blade style hoops.
Brawn and the team cited the blade hoop as being part of the
compromise of the W01 causing CoG issues. The double decked diffusers
of 09/10 were no longer available to the teams in 2011 being banned
by the FIA.

With DRS taking the place of 2010's F ducts systems in
order to reduce drag, the aerodynamics of the car before the rear
wing would be paramount. Mercedes unlike most of their competitors
positioned their DRS actuators in the endplates leaving the wing
planes free of any obstructions or moving parts. Mercedes did however
have problems both the actuation of DRS and problems with the wing
aerodynamically especially it would seem with Michaels setup. A
larger angle of attack chiefly to be blamed with aero balance being
affected when DRS was deactivated in the braking phase. As the top
plane snapped shut downforce should be restored allowing a stable
turn in. However as in aeronautics if you run too high an angle of
attack the wing stalls and loses aero efficiency. Both car stance
(through suspension setup) and AoA can be blamed for the stall that
was occurring, as soon as the wing pitched to the right angle the
airflow reattached and downforce is restored.

Perhaps one of the most controversial
aerodynamic elements at the end of 2010 and carried on rumbling into
2011 were the flexi front wings being used by the Red Bull and
Ferrari teams. Most of the teams found it incredible the wings were
making it through deflection tests but even when the FIA increased
the load/deflection tests they still passed. McLaren's 2011 contender (MP4-26) also ran
with a Front flexi wing but not to the same degree as the RB7.
Mercedes were once again late to the party and it was Germany before
the team started testing/using their own iteration. Whilst on the
subject of front wings Mercedes really played with 2 front wings for
the start of the season with one of these having a hole in the main
body of the wing. See Craig Scarboroughs article on this:
http://scarbsf1.com/blog1/2011/03/11/mercedes-w02-new-front-wing-analysis/

Above: Front Wing with hole in the main element

The Sidepods entries were angled inward
toward the tub encouraging airflow around the Sidepods. The nosecone
took further influence than the W01 from Red Bulls designs with a
higher much flatter nose in order to drive more air under the car and
even more pronounced ridges running longitudinally around the
suspension.

What i found strange from the original
test car were the sidepod airflow conditoners were very small
(vertically) of which my only prognosis was they wanted to get as
much more air toward the rear wheels rather than concentrating the
flow at the sidepod itself. These were
replaced at the last pre season test with more conventional height
conditioners.

The W02 took the W01's moving wheel
base throughout 2010 and decided on a stunted short wheel base. The
short wheel base could attribute to some of the issues the team had
both with CoG, aerodynamic deficiencies and tyre degradation. With
Pirelli re entering the sport and taking over from the out going
Bridgestone era the focus for tyre degradation in 2011 was always
destined to take a front seat. Tied to this was the FIAs introduction
of a weight distribution ruling in which mandates a 46/54 split. This
was done so that teams didn't steal a march on another by stumbling
across the perfect tyre balance and causing a development war between
the teams to find the perfect balance. Although the teams had decided
to omit KERS from their cars in 2010 it made a triumphant return in
2011 and Mercedes had been working on improving theirs with the
system also reduced to around 24kgs.

Above: The original Mercedes WO2 Exhaust design

Their original exhaust much like their
rivals exited rearward but seemed to pointed further outward toward
the wheel/tyre than say Red Bull perhaps in an attempt to seal the
diffuser edge. The second version of their exhaust taken to the last
pre season test was much further forward, exiting out of the side of
the Sidepod encouraging airflow across the floor toward the rear of
the car enmass with the airflow already pushing around the side of
the Sidepods. The movement of the exhaust further forward could also
be in response to their short wheel base. A small vertical strake in
front of the wheel helped to navigate the airflow inbound toward the
region above the diffuser.

Above: The WO2's second version of the exhaust

It took Mercedes until Valencia to
converge on the Red Bull solution who had their exhausts exiting much
more rearward and enclosed in a tunnel above the floor to the outside
edge of the floor sealing the diffuser much further back and
eliminating the effects of tyre squirt (see my tyre squirt article).
Even with the FIA curtailing the off throttle effect this remained
the most effective way of getting a diffuser sealing effect.

Mercedes GP found in 2010 as with the
other Mercedes powered cars using the exhaust plume to enhance
downforce was unpredictable. This is most likely down to the mapping
constraints and general attributes of the Mercedes powerplant in
comparison to the Renault, Ferrari and Cosworth power units. With
throttle sensitivity and overheating of bodywork all being issues for
the Mercedes powered cars. The problem with modern F1 is the lack of
testing and the cost implications of taking test parts to the
circuit. On the other hand some teams throw caution to the wind and
will take more physical parts to a race weekend to test than others.
The problem with assessing exhaust plume airflow in simulation is
getting the simulation right after all the exhaust is ballistic and
changes based on throttle input make using the exhaust plume an
aerodynamic advantage by exiting into atmosphere very much a driver
controlled entity. Enter Off throttle blowing something not only the
Mercedes teams were doing but something that definitely helped those
using Mercedes engine to narrow the gap to their rivals. Using off
throttle blowing helps to keep a continuous flow over the diffuser,
energizing the boundary of the diffuser and helping to draw more air
through the diffuser.

Above: (Top & Middle) shows the solution's Mercedes used to enhance EBD running an exhaust channel on top of the floor at the extremities of the diffuser. (Bottom) Shows the heat treatment added to the exterior of the diffuser to help with heat demand placed on the area by the exhaust position. Mercedes version of EBD ran much shorter on the floor than say the Red Bull variant which may be due to exhaust tuning requirements of the Mercedes engine.

2012

Mercedes began their 2012 campaign in
quite a strange manner using the W02 at the first test. This allowed
the team to correlate tyre data from 2011 with the new Pirelli
compounds of 2012. Apart from tyre data, testing with an old car
offers little benefit as the new car differed significantly in
wheelbase. The WO3 for all in tense and purposes should have sorted
most of Mercedes 2011 problems with a years running on the Pirelli
tyres, a new simulator and an enhanced team with new members of staff
during the design phase of the WO3.

The largest innovation at the start of
this season came from the Mercedes team in the shape of the Double
DRS (DDRS) system. Part of the system had been tested at the end of
season test in Abu Dhabi but most passed it off when the drivers
complained of difficulties when entering the braking and turning
phase. This device then muted the 'W' duct (as the airflow pattern
looks like a W) used the driver cooling hole as a method of passively
blowing the front wing. Air entering the cooling slot passes down the
wing pylons and out of a slot on the underside of the wing. However
when this test took place they were using the WO2, for the WO3 the
team had also integrated pipes which run the length of the car
joining the Front wing with the rear wing meaning that DRS plays a
part in the activation of the system in a similar manner to the
original F duct concept found on the McLaren etc during 2010. The
Lotus team protested DDRS but the system was deemed legal due to the
driver not being part of the activation process like the original F
ducts demanded and rather the DRS being active or inactive provided
the switch for drag reduction. If you have followed my work on Final
Sector since the start of the season you may see that I don't fully
subscribe to the Mercedes Front wing DDRS function others do.

How i believe Mercedes DDRS works

This is my theory and is based upon
techniques used in aircraft like blown flaps, circulation control wings, boundary layer control etc.
Below I'll aim to explain my ideas further/better than I did in my
original article: http://finalsector.co.uk/mercedes-super-drs-f-duct/

I must add that this is a theory and
please feel free to dismiss it over the conventional theory.

My theory is based on the slots under
the front wing making the wing work when blown. This is based on the
assumption that when Mercedes originally tested the 'W' duct it was
in order to create additional downforce aswell as reducing drag. Wings
can only create so much downforce, this can either be done by
dimensionally adding more wing or by increasing the angle of attack.
The size of the flaps available to F1 designers is heavily restricted
in order to limit the downforce available, they can add gurney flaps
but these will add drag and so on the front wing are usually limited
in size. Wing angle of attack (AoA) can effect how much
downforce is generated but once again at the compromise of drag. I'd
guess 15 degrees is about the stalling level of a wing (ie the point
at which it won't create additional downforce and stalls) if you were to blow
the rear face of the wing you can elevate the wing angle by perhaps
another 5 degrees before it stalls. This gives you the advantage of
being able to run a higher AoA than if you didn't blow it, resulting
in a net increase in downforce.

Above: Cascadeless Front Wing adopted from Montreal onwards

Since Montreal, Mercedes have run
their front wing without the cascades which again highlights that
they may have been creating too much front end downforce and the
cascades creating drag as a net result. (They also changed their
wing pylon design to a very McLaren-esque design) I believe the wing
from the WO2 with the hole in front of the wing planes paved the way
for this, with the designers wanting the air to be forced in behind
the main planes to allow a higher AoA. Being able to do this without
the need for the through hole would be more efficient.

Above: Mercedes WO2 Front Wing with blow through hole

So how does this all work with DRS i
hear you say well i believe the original 'W' duct is intrinsically
linked with the DDRS tubing from the rear wing:

Airflow captured in by the nosecone
cooling hole is sent down the wing pylons and exits underneath the
wing allowing for a higher AoA

When DRS is deployed the airflow that
usually goes down the pylons toward the front wing is sucked/pulled
past and sent along the tubing to the rear wing.

Above: Image of the tubing that runs inside the Sidepod from the front wing through to the rear wing endplates

This has two effects: it augments the
airflow around the DRS flap by laterally blowing across the underside of the top wing plane enhancing the DRS effect but more importantly without the blown
effect on the underside of the front wing, the wing has too high an
AoA and stalls shredding both downforce and drag.

Some of Nico's quickest lap times at the start of the season saw him deactivating DRS prior to the braking phase which if my theory is correct would see the front wing becoming blown restoring front end downforce and balance for cornering/braking.

Mercedes DDRS is really a qualifying enhancement and if my theory serves correct becomes more of a hamper as the race goes on. This is due to pitch angle, as the fuel burns off during a race the AoA on wings alter ever so slightly which puts the car through an evolution process. This could be part of the reason for Mercedes tyre struggles (again speculation).

Although initially the Lotus system was hailed a DDRS it would now appear it is very much a passive F duct system much like the one that Mercedes ran on the WO2 so if Mercedes are prepared to take their closest championship rivals on there is no reason why they couldn't employ a similar system to reduce drag on the lower plane like Lotus: http://somersf1.blogspot.co.uk/2012/08/lotus-e20-passive-f-duct-system.html (TDRS anyone?)

DDRS may have be becoming the
WO3's Achilles heel as any upgrades placed on the car will need to be
balanced with the aero shift that is created by the device. This
however is not the largest problem in play for Mercedes and that more
likely stems from the polar opposite of the WO2 with the current car
having a very long wheel base. The wheelbase can effect everything
from suspension geometry, to tyre wear, to how downforce is created
amongst many other things. The WO2 suffered in terms of cooling due
to its wheelbase as the Sidepods were too small compromising internal
dynamics. This season the Sidepods are much bulkier to both
accommodate the additional cooling requirements and the DDRS tubing.
The boundary layer build up along the top surface must be fairly
significant due to the length of the Sidepods. However having the
exhaust exit on top of the Sidepod will at least enhance the airflow
travelling along the top of the sidepod.

Unlike other teams that use the Coanda
style exhaust positions and have adopted the vortex generator fins on
top of the Sidepod Mercedes don't need these as the airflow doesn't
need to be destabilized or guided in a downwash effect as the Sidepod
remains fairly high to the rear. Mercedes haven't upgraded their car
at the rate of their opposition with their major upgrade package
featuring at Monaco:
http://finalsector.co.uk/monaco-gp-technical-roundup/
and the race after in Montreal saw the team drop the front wing
cascades most likely in response of balancing the upgrades from
Monaco.

Mercedes have a difficult decision to
make with now only 9 races of the season left, unlike their
counterparts Mercedes have stood firm in their design ethos whilst
others have converged on very similar exhaust design paths. This is
something that the team did in 2011 too leaving them trailing to
their rivals. They claim that by not adding upgrades they can better
understand the effects of the Pirelli tyres, this all sounds well and
good but whilst you stand still in F1 your are actually moving
backwards in comparison to your opposition. Mercedes need to make a
decision on where they need to finish this season as upgrades are the
only way to stop the like of Williams, Sauber, and Force India
overtaking them in the title battle. They could do the same as Honda
in 08 and shift focus now to their 2013 contender but this could be
at the cost of lucrative FOM money.

Conclusion

From the outside looking in it would
appear that Mercedes internal processes take too long to implement
leaving them at odds when either following their own design path or
trying to converge on others. This problem is systematic and stems
from the gestation period between Honda and Mercedes as highlighted
here by Ross Brawn after a hard fought 2009 campaign:

"In the interests of fairness,
we simply said that every department had to lose 40 per cent,"
said Brawn, something regretfully. "It was as crude as that. We
had no other mechanism to go through the company and say, two from
here, five from there."

A lot of good people were lost in
that cull, not necessarily big names, but engineers that were a
crucial part of forming a team's backbone, that helped ensure their
departments could run with a certain degree of autonomy. The group
that was left was not only shellshocked by the cull and the loss of
several key working relationships, but had to establish a whole new
dynamic.

Into that mix throw in the departure
of a senior member of the engineering staff - Jorg Zander, who left
early last year - and it's not really so surprising in hindsight that
the car was a little unadventurous. Its gearbox, for example, was too
short to make really aggressive use of the twin diffuser”

As Ross alludes to here Brawn GP didn't
simply lose tea ladies in the cull, the staff lost were integral to
the team and meant a total change in philosophy this would then be
followed by the introduction of Mercedes who would want processes
done their way. Mercedes like Honda before them will be thinking
long and hard about their involvement at team level and the rewards
team ownership brings. As I have been writing this article word has
spread that Mercedes intends to step back from it's team involvement
from 2013 onwards which shows that the money men in Stuttgart now
realise that just like Renault, F1 can bring success without a having the need for a team.

You may well have already read my
previous article on my feelings regarding the Lotus DDRS system
http://somersf1.blogspot.co.uk/2012/07/lotus-e20-ddrs-hockenheim.html,
as always the problem with not being able to see these items in the
flesh leaves doubt over their actual purpose. As more images have
become available it's become clearer that my original thoughts on the
system although perfectly valid and usable are actually flawed. The
trouble with fluidic switching systems is that there are so many ways
in which you can move air from one location to another that the
waters muddy.

Compounding this, Lotus had already
stated that their system utilises the same loophole that the Mercedes
DDRS system works within (ie using the DRS movement as a part of the
flow adjustment for another device). It is plausible that is a Red Herring
with the addition of the periscope simply acting as it's own device
reducing drag by blowing the underside of the Rear Wing's main plane reducing drag passively above a certain speed threshold and then when DRS is activated it simply augments the DRS effect. I'll
explain this first and then go on to explain how both this theory and
my original one could be combined.

As we can see in the images above small
slots in the periscope blow the central section of the main plane
reducing drag in that region of the wing. (Flow Viz is splayed in this region denoting the reduction in drag) This concept mimics the
original F Duct principles in how drag is reduced on the rear wing
but falls short of being as powerful. The original F Ducts had much
larger slots on the rear wing plane in order for the drag to be
reduced over a larger area. The original F Duct also required the
driver to act as a switch effectively turning on or off the rear
wing, this was outlawed as part of the regulation change back in
2011. The Lotus system is instead tuned to reduce drag at a certain
speed by specifically designing the engine cooling outlet. At lower
speeds the air consumed by the airbox inlet and ear ducts can escape
through the engine cover cooling exit. As the car reaches higher
speeds the air consumed becomes more than can be effectively
exhausted from the cooling exit and so air spills up the periscope
toward the rear wing reducing drag on the lower wing plane.

The rules were amended at the end of 2010 to stop the interaction of
shark fin engine covers with the wing planes and DRS was introduced
in response to the teams drive to reduce drag and increase
overtaking. With DRS now moving the whole top element creating a
union with the engine cover would obviously be very difficult anyway. The periscope however doesn't join to the wing frontally but on the underside and so circumnavigates this rule.

Using the periscope to blow the bottom
wing plane allows a dual drag reduction system with the lower plane
being blown as soon as the car reaches a pre determined speed and DRS
obviously adding the larger drag reduction element as and when it's
activated. Passive F Ducting to the rear wing will provide a
marginal advantage during qualifying where DRS is unlimited simply
boosting the DRS effect but it's during the race where the system
should give Lotus the largest advantage. On circuits like Spa and
Monza they will be able to increase their wing angle of attack
creating more downforce during cornering and have less drag on the
straights than their counterparts where DRS is unavailable.

The addition of the Airbox Ear ducts
are as I mentioned in my previous article paramount in terms of
balancing the system due to Airbox Spillage. As the driver comes off
throttle airflow is impeded in the airbox entry and so tumbles off
the sides of the airbox down the engine cover creating a turbulent
airflow toward the rear of the car and most importantly disturbs the
airflow around the rear wing. The ears that Lotus have employed
capture this airflow in order to keep the airflow heading toward the
rear wing with a laminar flow which in turn will help create downforce more
effectively in the braking and turning phase (Credit Gordon Mccabe
-
http://mccabism.blogspot.co.uk/2011/10/airbox-spillage-and-fluidics.html)

Pit Falls & Problems

Although McLaren were the first to
introduce the F Duct in 2010 it's widely regarded that once
integrated that the Renault team (now Lotus) had the most effective F
Duct system. This obviously puts them in great stead in terms of
understanding how best to utilise such devices. The problem with a
passive system over a controlled system (like the original F Duct) is
that the system is very much dependent on airspeed through the
airbox. This may cause problems in the form of tunabilty especially
when we consider the difference between the ability of a car during
qualifying with a low fuel load and that of a car full of fuel. We
also have to consider the high speed nature of circuits like Spa and
Monza have corners with high speed exits and so reducing drag on
corner exit as the passive duct inadvertly activates could be
catastophic. This means that the Periscope Duct needs to be tuned to
activate at a relatively high speed and as such won't have the same
drag reduction capability the older F Duct did.

Combination of the above with my
original theory

If we take the team at their word that
the system employs the DRS as a lever to leverage another element in
the system I believe that both
variants of my thoughts could be in play. The problem with this is
that we are yet to see a close image of the DRS open in order to
establish if the wing covers any holes in the wing plane.

This
would work by exhausting the airflow from the airbox inlet through
the cooling hole and as it the exit becomes too small for the airflow
exiting the air moves up the periscope and reduces the drag on a
portion of the lower wing plane. When DRS is activated and a hole is
opened on the rear wing plane a more positive draw would be created
on the airflow from the airbox inlet drawing more air up the
periscope and out of the slots. This would increase the
effectiveness of drag reduction on this region giving a more positive
DRS effect. I believe this offers the more balanced effect with a
transition phase of drag reduction from both avenues.

In
Summary

Until
further evidence presents itself the exact operation of the device is
speculation but it's application is something I'm sure the other
teams will be looking closely at as in a year where the grid is so
close even the smallest advantage could play a large hand in the
results of the latter races. McLaren have already hinted that they
haven't ruled out the possibility of such a system before the end of
the season. One thing is however clear that systems linked to DRS
won't be prevalent in 2013 as the teams have unanimously voted to
outlaw them. This will be passed to the technical working group
(TWG) who will work with the FIA in order to constrain such usage by
adjustment of the regulations. This however doesn't prevent the usage of the passive element of the system via the pylon being exploited.

Credit to Nick McDowell for the image pointing out the slots in the periscope

Whilst I'm trying to keep atop of the blog you may have noticed of late that there is less content appearing. For those of you that haven't realised, most of my work has now been moved over to Motorsport.com where I'm working with Giorgio Piola.

I'm still doing the technical image gallery for each GP with the continued support of friend of the site Sutton Images. However, as always my time is limited and so this might not be updated as quickly as it once was, so keep checking back.

As some of you may have found out already I'm also working with the Missed Apex crew on their podcast from time-to-time, either doing race reviews or dedicated 'Tech Time' shows.

I've embedded the latest version of the podcast below and will update this a frequently as I appear. However, please head over to Itunes if you want it to appear in your player when episodes are available. The show is great to work on and has a great lineup of 'regulars' but has also enticed some bigger names recently too, with Will Buxton and Bradley Philpot on shows during the summer break.

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